1. Field of the Invention
The present invention relates to a binding device for snowboard, and more particularly, to a binding device for snowboard, which is constructed to be rotable with respect to a snowboard.
2. Description of the Related Art
A binding device is used for fixing shoes to a snowboard. The binding device comprises a holder portion 62 for holding a shoe and a mounting plate 63 for mounting the holder portion 62 to a snowboard SB as shown in FIG. 15. The mounting plate 63 is fitted to a fitting hole 62a provided in the holder portion 62 and fixed to the snowboard SB by tightening plural screws 61 to screw holes provided in the snowboard SB.
Although not shown, a tooth arrangement is provided on the periphery of the fitting hole 62a in the holder portion 62a, and the same tooth arrangement is provided on the periphery of the mounting plate 63. By engaging both the tooth arrangements freely, the angle of the holder portion 62 relative to the snowboard SB, that is, the angle of the binding device 60 can be adjusted as indicated by arrows in the figure.
However, in such a binding device 60, although the angle of the holder portion 62 can be adjusted when it is attached, the angle thereof cannot be adjusted during use of the snowboard SB because the holder portion 62 is fixed to the snowboard SB with the screws 61.
Thus, the motion of the binding device 60, in other words, the motion of the foot is limited upon snowboarding and its snowboarding way is also restricted. If the foot is fixed upon snowboarding, a burden is applied to the knee, ankle or the like, so that, particularly, when a snowboarder falls down, the bone of his or her knee or ankle may be broken.
To solve such a problem, Japanese Patent Application Laid-Open No. 2003-24496 has proposed a setting device for a snowboard binding, which allows a binding device to rotate with respect to a snowboard SB during snowboarding.
The setting device 70 includes a base member 71 in which screw holes 71a for mounting to the snowboard and screw portions 71b for fixing a press-fit plate 74 are formed, as shown in FIG. 16. The base member 71 is fixed to a predetermined position of the snowboard with the screw holes 71a and screws (not shown) The base member 71 accommodates a bearing 72, and a rotating member 73 is mounted on the top of the bearing 72. The press-fit plate 74 covers the top of the rotation member 73 and holds the rotating member 73 rotatably.
The press-fit plate 74 has a through hole 74a and a cutout portion 74b through which a binding mounting portion 73c of the rotating member 73 is to be inserted. By mounting the press-fit plate 74 over the top of the rotating member 73, the binding mounting portion 73 and a projecting portion 75b of the rotating member 73 pass through the press-fit plate 74, so that the press-fit plate 74 makes a pressure contact with a jaw portion 73b of the rotating member 73.
The press-fit plate 74 which keeps a pressure contact with the jaw portion 73b of the rotating member 73 is fixed to the base member 71 by inserting the screw portions 71b of the base member 71 through screw holes in the press-fit plate and tightening nuts 74c. 
A screw hole is formed in the projecting portion 75b of the rotating member 73, and when a screw 75a is tightened from above, the screw 75a makes a pressure contact with the top face of the press-fit plate 74. Consequently, if a predetermined rotation force is applied to the rotating member 73, the rotating member 73 rotates with respect to the base member 71. Reference numerals 73a in FIG. 16 denote a screw hole for attaching the binding (not shown).
In the setting device for the snowboard binding, the angle of the binding can be changed freely because the rotating member 73 is constructed to be rotatable. Thus, a user can ride on/off a ski lift with the binding attached to the snowboard or move smoothly on a place without any slope, and during snowboarding, the binding (rotating member 73) can rotate with respect to the snowboard, so that user can enjoy free snowboarding.
However, in the above-mentioned setting device 70, once the binding (rotating member 73) rotates with respect to the snowboard, the user cannot help relying on his or her experiences or sense to return the binding (rotating member 73) to a reference position at an initial period of snowboarding. For the reason, this setting device is difficult to handle for a beginner or child because he or she cannot find out the reference position easily. Further, no means for restricting the rotation of the binding (rotating member 73) with respect to the snowboard is provided. For this reason, the binding (rotating member 73) is rotated more than necessary at the time of snowboarding, which provides a problem that the setting device cannot be handled easily.
Further, there is a danger that if the binding (rotating member 73) is rotated more than necessary due to an impact by fall-down or the like, an excessive load is applied to the joint of the knee, ankle or the like, thereby inducing an injury.